About this 3D model

This model can be used as a starting point for making a two piece mold that can be used to cast plaster, Sugru, modeling clay, etc and is part of the Learning In A Makerspace chapter of my new book "[The Makerspace Workbench](http://shop.oreilly.com/product/0636920028147.do)" from Maker Media! Simply open the models in 3D CAD and subtract the desired part. Apply a small amount of petroleum jelly prior to casting and pour away!